My key stopped working when I went to start the car and the alarm wouldn’t stop going off until I unplugged the battery the car wouldn’t start either (before I unplugged it). I put a new battery in the key but nothings changed, it I put the ignition on then connect the battery I have about 25 seconds until the alarm starts pinging again also has like a timer ticking sound before it goes off,  just wondering if anyone knows how to fix as it’s doing me eddin ahah and I don’t have the owners manual and don’t know the code to the keypad

You can try contacting subaru dealer they should have a code on file. Assuming previous owners didn't change it. I assume you don't have spare fob.